ExpressionBuilder.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / Compilation / ExpressionBuilder.cs / 1 / ExpressionBuilder.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Web.Compilation { 
    using System; 
    using System.Security.Permissions;
    using System.CodeDom; 
    using System.Collections;
    using System.Collections.Specialized;
    using System.ComponentModel.Design;
    using System.Web.Configuration; 
    using System.Reflection;
    using System.Web; 
    using System.Web.Hosting; 
#if !FEATURE_PAL
    using System.Web.UI.Design; 
#endif // !FEATURE_PAL
    using System.Web.UI;
    using System.Web.Util;
 

    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)] 
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level=AspNetHostingPermissionLevel.Minimal)] 
    public abstract class ExpressionBuilder {
        private static ExpressionBuilder dataBindingExpressionBuilder; 

        internal virtual void BuildExpression(BoundPropertyEntry bpe, ControlBuilder controlBuilder,
            CodeExpression controlReference, CodeStatementCollection methodStatements, CodeStatementCollection statements, CodeLinePragma linePragma, ref bool hasTempObject) {
 
            CodeExpression codeExpression = GetCodeExpression(bpe,
                bpe.ParsedExpressionData, new ExpressionBuilderContext(controlBuilder.VirtualPath)); 
 
            CodeDomUtility.CreatePropertySetStatements(methodStatements, statements,
                controlReference, bpe.Name, bpe.Type, 
                codeExpression,
                linePragma);
        }
 
        internal static ExpressionBuilder GetExpressionBuilder(string expressionPrefix, VirtualPath virtualPath) {
            return GetExpressionBuilder(expressionPrefix, virtualPath, null); 
        } 

        internal static ExpressionBuilder GetExpressionBuilder(string expressionPrefix, VirtualPath virtualPath, IDesignerHost host) { 
            // If there is no expressionPrefix, it's a v1 style databinding expression
            if (expressionPrefix.Length == 0) {
                if (dataBindingExpressionBuilder == null) {
                    dataBindingExpressionBuilder = new DataBindingExpressionBuilder(); 
                }
                return dataBindingExpressionBuilder; 
            } 

            CompilationSection config = null; 

            // If we are in the designer, we need to access IWebApplication config instead
#if !FEATURE_PAL // FEATURE_PAL does not support designer-based features
            if (host != null) { 
                IWebApplication webapp = (IWebApplication)host.GetService(typeof(IWebApplication));
                if (webapp != null) { 
                    config = webapp.OpenWebConfiguration(true).GetSection("system.web/compilation") as CompilationSection; 
                }
            } 
#endif // !FEATURE_PAL

            // If we failed to get config from the designer, fall back on runtime config always
            if (config == null) { 
                config = RuntimeConfig.GetConfig(virtualPath).Compilation;
            } 
 
            System.Web.Configuration.ExpressionBuilder builder = config.ExpressionBuilders[expressionPrefix];
            if (builder == null) { 
                throw new HttpParseException(SR.GetString(SR.InvalidExpressionPrefix, expressionPrefix));
            }

            Type expressionBuilderType = null; 
            if (host != null) {
                // If we are in the designer, we have to use the type resolution service 
                ITypeResolutionService ts = (ITypeResolutionService)host.GetService(typeof(ITypeResolutionService)); 
                if (ts != null) {
                    expressionBuilderType = ts.GetType(builder.Type); 
                }
            }
            if (expressionBuilderType == null) {
                expressionBuilderType = builder.TypeInternal; 
            }
            Debug.Assert(expressionBuilderType != null, "expressionBuilderType should not be null"); 
 
            if (!typeof(ExpressionBuilder).IsAssignableFrom(expressionBuilderType)) {
                throw new HttpParseException(SR.GetString(SR.ExpressionBuilder_InvalidType, expressionBuilderType.FullName)); 
            }
            ExpressionBuilder expressionBuilder = (ExpressionBuilder)HttpRuntime.FastCreatePublicInstance(expressionBuilderType);

            return expressionBuilder; 
        }
 
        // 
        // Public API
        // 

        public virtual bool SupportsEvaluate {
            get {
                return false; 
            }
        } 
 
        public virtual object ParseExpression(string expression, Type propertyType, ExpressionBuilderContext context) {
            return null; 
        }


        public abstract CodeExpression GetCodeExpression(BoundPropertyEntry entry, 
            object parsedData, ExpressionBuilderContext context);
 
        public virtual object EvaluateExpression(object target, BoundPropertyEntry entry, 
            object parsedData, ExpressionBuilderContext context) {
            return null; 
        }

    }
}

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